1. Field of the Invention
This invention relates to a cover for a leaf switch, and more particularly to a cover for a leaf switch capable of sealing and enclosing contact elements of the leaf switch effectively to prevent dust reaching the contact elements, while allowing the leaf switch to operate effectively.
2. Description of the Prior Art
Recently, large numbers of different kinds of micro-switches and leaf switches have been used in various electronic and electrical devices such as electronic computers, electronic acoustic units and the like. The use of such switches is rapidly increasing.
Micro-switches conventionally used are generally constructed to enclose their contact mechanism in a small case formed of plastics, to make them more dust-proof. However, in such a conventional micro-switch the contact mechanism in the small case must be operated from the outside of the case. This results in the conventional micro-switch being disadvantageous in that its construction is complicated, its strength is poor, it lacks durability and is costly.
Leaf switches, on the other hand, generally include a switch mechanism which comprises spring-loaded contact elements constructed in a simple manner and open to the atmosphere. Leaf switches tend to last longer, work better and cost less than micro-switches. However, the conventional leaf switch is disadvantageous in that dust is apt to adhere to contact portions of the contact elements, because the contact elements are open to the surrounding atmosphere. In addition, a voltage is applied to the contact portions during actuation and further promotes the adhesion of dust to the contact portions. Resistance therefore builds up due to contact failure or poor conduction at the contact portions. Thus, the conventional leaf switch cannot effectively switch when a low current is flowing.